HU219047B - Vacuum brake-force rising or reinforcing device for motor vehicles - Google Patents

Abstract

The present invention relates to a vacuum brake booster or brake booster for motor vehicles. In order to detect whether the external operation of an electromagnetically controlled brake booster has actually been completed after an already performed externally assisted braking, electrical switching elements are used according to the invention, the control signals of which affect the power supply to the electromagnet (20). ŕ

Description

The present invention relates to a vacuum brake booster or a brake booster for motor vehicles. The brake booster has a booster housing and a control housing. The interior of the amplifier housing is divided by a movable wall into a vacuum chamber and a working chamber. The control housing carries the movable wall. The control housing comprises a control valve for controlling the differential pressure acting on the movable wall, comprising at least two sealing seats which cooperate with a resilient valve body. The control valve may be actuated on the one hand by an operating rod and on the other hand by an electromagnet independent of the operating rod, the anchor of which cooperates with one of the sealing seats by means of power transmission.

Such a vacuum brake booster is known, for example, from European Patent Application 0 478 396 A1. The electromagnet which actuates the sealing seat, the lifting of which from the valve body allows air to enter the working chamber, is, in one embodiment of the present patent application, located outside the control housing on the actuating rod. However, the known brake booster does not include elements that allow a controlled initiation, interruption or completion of an external braking process. In addition, active control of the brake booster mode is not possible.

It is therefore an object of the present invention to provide a vacuum brake booster which ensures that the external actuation of an electromagnetically controlled brake booster is effectively completed, in particular after an external power assisted braking has already been performed.

According to the present invention, this object is achieved by providing the brake booster with electrical switching elements whose control signals affect the power supply to the electromagnet and, in particular, enable it to be switched off. Preferably, the coupling elements comprise a microswitch on the valve plunger and an actuator located on the control housing or control housing.

The switching path of said microswitch in an advantageous improved embodiment of the invention is extended so that the switching elements can be operated by relative movement between the valve plunger and the control housing. It is particularly advantageous here that the actuator is movable relative to the control housing and is spring-biased against the actuation direction. The actuator then rests on a stop fixed to the brake booster housing under the pretension of a compression spring such that there is an axial play between it and the control housing at its end toward the microswitch.

In a further preferred embodiment of the invention, the actuator is effectively compensated by providing the actuator with two telescopically guided spring-biased components, in particular a control bar sealed in the control housing, cooperating with the spring-loaded actuator formed by a fixed sleeve coaxial with the operating rod and cooperating with the microswitch. This solution also effectively prevents damage to the microswitch.

The present invention will be described in more detail with reference to the drawings, in which:

Figure 1 is a longitudinal sectional view, partially broken away, of an embodiment of the vacuum brake booster of the present invention;

Figure 2 is a view of each of the actuation stages of the vacuum brake booster of the present invention shown in Figure 1.

The housing 1 of the vacuum brake booster according to the invention is only schematically indicated in the figures by an axially movable wall 2 dividing it into a working chamber 3 and a vacuum chamber 4. The axially movable wall 2 is formed by a diaphragm plate 8 made of a deep-drawn plate and an elastic membrane 18 resting thereon. The diaphragm 18, not shown in detail, forms a seal between the outer periphery of the diaphragm plate 8 and the brake booster housing 1 as a rolling membrane.

A control valve 12 actuated by an operating rod 7 is housed in a control housing 5 which is sealed in the housing of the brake booster and carries the movable wall 2. The control valve 12 comprises a first sealing seat 15 formed on the control housing 5, a second sealing seat 16 formed on a valve piston 9 connected to the operating rod 7, and a valve body 10 cooperating with the two sealing seats 15, 16. The valve body 10 is pressed against the sealing seat 15, 16 by a valve spring 22 on a support ring 21. The working chamber 3 can be connected to the vacuum chamber 4 via a channel 28 extending sideways in the control housing 5.

The braking force is transmitted on a front side by a rubber-resilient return disc 6 on the control housing 5 and a pressure flange 14 with a head flange 23 on the actuator piston of the brake master cylinder (not shown) located on the vacuum side of the brake booster housing.

The recovery spring 26, schematically depicted in the drawing, which rests on a vacuum flange 1 of the brake booster housing, holds the movable wall 2 in the initial position shown. In addition, there is a second compression spring 27 which rests on the operating rod 7 and on the retaining ring 21 and whose spring force biases the valve plug 9 or its sealing seat 16 relative to the valve body 10.

In the control housing 5, an approximately radial channel 29 is provided so that the working chamber 3 can be connected to the atmosphere when the control valve 12 is actuated. At the end of a braking process, the reciprocal movement of the valve piston 9 is limited by a transverse member 11 which rests on the stop 38 formed in the housing 1 of the brake booster when the vacuum brake booster is released.

A third sealing seat 24 is provided radially between the first sealing seat 15 and the second sealing seat 16 to actuate the external actuation of the vacuum brake booster according to the invention independently of the operating rod 7. The sealing seat 24 is actuated by the electromagnet 20, which is preferably located in an axial pot-shaped extension 25 of the piston 9,

EN 219 047 Β and accordingly can be displaced in the control housing 5 together with the piston 9. The electromagnet 20 consists of a coil 46 located within the extension 25 and a displaceable cylindrical anchor 31 therein. The anchor 31 is guided on the one hand within the coil 46 and on the other end 30 of the extension 25. The external actuating force exerted by the electromagnet 20 is transmitted to the third sealing seat 24 by a transmission sleeve 33 which lies axially on the anchor 31 and which has a distal end forming the sealing seat 24.

Between the valve piston 9 and the transmission sleeve 33, a spring 40 is provided which holds the anchor 31 in its initial position. In this position, the third sealing seat 24 is axially offset from the second sealing seat 16 formed on the piston 9. The closing portion 30 guided in the control housing 5 rests on an intervening transmission disc 61 via an intervening transmission disc 61 and allows transmission of the input power applied to the actuating rod 7 to the return disc 6.

Finally, the illustrated embodiment of the vacuum brake booster according to the invention includes electrical switching elements which are particularly important in braking processes where, in addition to actuation by the driver, . It is of particular importance that the coupling elements are actuated each time the brakes are applied. At the same time, care must be taken to ensure that the electromagnet 20 is securely disconnected after completion of the external force assisted braking process. The coupling elements in question are formed here by a microswitch 55, preferably fitted on the piston 9, having two coupling positions, and an actuating member 56 which is actuated by translational movement and is sealed in a bore in the control housing 5 and guide 67, and cooperates with a fixed stop 58 relative to the brake booster housing. The stop 58 may be formed, for example, by a radial collar on the back of the brake booster housing. There is a compression spring 57 between the actuator 56 and the control housing 5 and guide member 67, so that the end of the actuator 56 farther away from the microswitch 55 is biased against the stop 58. Here, the actuator 56 is particularly preferably formed by two telescopically guided elements, the actuator rod 59 and the sleeve 60, which are pressed outwardly axially by a second compression spring 66. The abutment member 58 is an actuator bar 59 whose movement in the control housing 5 and guide section 67 is limited by a radial flange 64. The flange 64 cooperates with a tensioning ring 65 in the control housing 5 and guide section 67 respectively. Another element for actuating the microswitch 55 is a sleeve 60, which is guided on the actuator bar 59 and accommodates the second compression spring 66.

Finally, as shown in Figure 1, in the embodiment of the brake booster shown here, the control housing 5 is formed of two parts and comprises a guide portion 67 and a front housing portion 63. The guide portion 67 is guided in the brake booster housing and has a control valve 12 therein together with an electromagnet 20. The front housing portion 63 is connected in a form-locking manner to the guide portion 67. The aforementioned gear wheel 61 allows the actuator force generated by the driver via the valve piston 9 to be added to the amplifying force exerted by the movable wall 2. The movement of the gear disc 61 in the opposite direction to the actuation direction is limited by the stop surface or the annular surface 62 formed in the front housing part 63 so that it is possible to move the valve piston 9 in the opposite direction to the actuation direction.

In the brake release position of the vacuum brake booster according to the invention, its components are in the position shown in Figure 1. Due to the action of the actuating rod 59 on the stop 58, the compression spring 57 is slightly compressed such that there is an axial distance or play between the flange 64 and the clamping ring 65. As shown in FIG. The microswitch 55 in its first switch position is axially supported on the sleeve 60. The control housing 5 or guide portion 67 and the valve plunger 9 all engage across the brake booster housing through a transverse member, while the closing portion 30 of the valve plunger 9 rests on the transmission disc 61. The transmission disc 61 is at a distance from both the stop surface and the ring surface 62 and the return disc 6.

If the driver now actuates the normal (partial) braking by actuating the valve piston 9, the valve piston 9 rises from the all-transverse member while the gear lever 61 is brought into contact with the retraction disk 6 (see Figure 2a). As a result of the relative movement between the valve plunger 9 and the control housing 5 or guide portion 67, the microswitch 55 moves away from the actuator 56 and thereby switches to its second switching position. The switching position of the microswitch 55 is reported by a control electronics (not shown) for controlling the electromagnet 20. If the electromagnet 20 is not actuated, this signal is used to verify the proper functioning of the switching elements (microswitches 55, actuators 56). As a result of relieving the compression spring 57, the actuating rod 59 is restored so that its flange 64 rests on the tensioning ring 65. Simultaneously, the second compression spring 66 pushes the actuator bar 59 and the sleeve 60 to the stop.

The full braking position triggered by the driver is shown in Figure 2b. is shown. Since the microswitch 55 is similarly, first of all, at a certain distance from the actuator 56 or the sleeve 60, therefore, its switching state does not change so that it remains in the second switching position. In the full braking position, only the distance between the coupling elements - the microswitch 55 and the actuator 56 - increases as the gear disc 61 is pushed into the rubber-elastic return disc 6.

HU 219 047 Β

2c. FIG. 4A is a complete braking position created by the driver's rapid actuation and triggered by simultaneous control of the electromagnet 20 by electronics not shown. As a result of the relative movement of the piston 9 relative to the control housing 5 and the guide portion 67, the microswitch 55 switches to its second switching position, allowing the electromagnet 20 to be activated. Due to the auxiliary air inlet to the working chamber 3, which is created by the further opening of the atmospheric sealing seat 16 formed on the piston 9 by actuation of the third sealing seat 24, the control housing 5 advances relative to the valve piston 9. Meanwhile, the cross member 11 is in an intermediate position with no contact between it and the control housing 5 or guide portion 67. As a result of the retraction force acting on the push rod 14, the return disc 6 is pressed into the recess 61 in the guide housing 67 which receives the gear disc 61 until it engages on the annular surface 62. Impact of the gear disc 61 prevents the transmission of the retraction force to the valve piston 9, so that the retraction force is no longer detectable on the actuating or braking pedal.

In the case of a slow brake release process (when the actuating force is released), the microswitch 55 is only switched when the actuator 56 or actuator rod 59 is in contact with the stop 58 (Fig. 1).

In the case of a rapid brake release process or when the actuating force is released during full braking by the control of the electromagnet 20 (Fig. 2d), the microswitch 55 is switched to the first switching position by the actuator 56 and the sleeve 60 respectively. The aforementioned electronics receive a signal about the switching process and generate a control signal, as a result of which the electromagnet 20 is switched off. The control housing 5 and the guide portion 67 are released by the transverse member 11 abutting against them, while the transmission disc 61 is pressed against the stop surface and the ring surface 62 by the resilient material of the return disc 6. The axial distance between the valve piston 9 or the end of the closure portion 30 and the transmission disc 61 corresponds to the brake release stroke required to release the brake device from full braking controlled by the electromagnet 20.

Claims (7)

PATENT CLAIMS Vacuum brake booster or brake booster for motor vehicles having a brake booster housing (1) having an internal space divided by a movable wall into a vacuum chamber (4) and a working chamber (3), which controls the pressure differential between the movable wall (2) and the movable wall (2). having at least two sealing seats (15, 16, 24) and a corresponding flexible valve body (10) actuating the control valve (12) and a force acting on one of the sealing seats (15) independent of the operating rod (7), An electromagnet (20) having an anchor (31), characterized in that it is provided with electrical switching elements which influence the power supply of the electromagnet (20), in particular by switching it off. Vacuum brake booster device according to claim 1, characterized in that it has variable-state switching elements controlled by a relative displacement between the valve plunger (9) and the control housing (5). Vacuum brake booster according to Claim 2, characterized in that the switching elements comprise a microswitch (55) mounted on the valve plunger (9) with two switching positions and an actuating element (56) located on the control housing or control housing (5). Vacuum brake booster according to Claim 3, characterized in that the actuator (56) is movable relative to the control housing (5) and biased against the actuation direction by a spring. Vacuum brake booster device according to claim 4, characterized in that the actuator (56) is prestressed by a compression spring (57) on a stop (58) fixed to the brake booster housing with an end thereof facing the microswitch (55). and an axial play between the control housing (5). 6. Vacuum brake booster according to any one of claims 1 to 5, characterized in that the actuator (56) is formed by two telescopically guided spring-biased components. Vacuum brake booster according to claim 6, characterized in that the actuator (56) is operably guided in the control housing (5) and cooperates with the stop (58) and is pre-tensioned on the actuator (59) by a spring. forming a sleeve (60) coaxial with the operating rod (59) and cooperating with the microswitch (55).